Summer has grown up in the shadow of her older sister Shannon. Shannon the great student. Shannon the success. Unfortunately, Shannon died before summer was even born (she suspects she is a replacement child, and the she never would have been born if Shannon hadn't been in that car accident). That makes it even harder to live up to everyone's perfect memories of a sister who isn't around to make mistakes.

But when she turns seventeen, Summer's Aunt Nic gives her an unexpected gift -- the journal that Shannon kept in the months before she died. Summer starts to find out that maybe her perfect sister wasn't perfect after all -- and that neither was their family. She's not sure whether she wants to find out some of the more shattering secrets, but once she starts, she can't leave the diary unfinished. She starts talking to people who knew Shannon, lancing open wounds that can finally begin to heal.

Summer's family has an exceptionally strong hold on their grief. Based on their reactions, it felt like Shannon's death had happened only a few years ago, rather than nearly two decades. It is this inability to move on, or to actively cope with the grief -- especially on the part of her mother -- that has Summer so alienated from life around her.

In THEN I MET MY SISTER, Summer sometimes seems impossibly wise, especially as she watches Shannon's agonies unfold on the page. Yet, most of the time, the characters are real and quirky, and it is easy to get caught up in their lives. The best part of the story is the relationship between Summer and her best friend Gibs. At first Gibs urges Summer to investigate the diary, but as Summer gets sucked into the trauma of the past, he's the one who's there to help her keep one foot in the present.